Migrating from the Email Settings API

This document covers the key differences between the
Email Settings API and the Gmail API. You can
use this guide to help migrate your app to the Gmail API.

Authorizing requests

Like the Email Settings API, the Gmail API uses the OAuth 2.0 protocol to
authorize requests. One key difference is that Gmail API permissions are
scoped to an individual user, rather than to the entire domain. This means
authorizing a domain administrator account does not allow you to migrate mail
for other users in the domain. Instead, you must use
standard service accounts with domain-wide authority
that are whitelisted in the Admin console to
generate the appropriate authentication token.